| 摘要 |
PROBLEM TO BE SOLVED: To enhance snow column shearing force of a limited groove area, and improve on-snow performance while securing excellent on-ice performance. SOLUTION: At least one rib shaped land part 6 of a block row includes a horizontal groove 5c, and an opening end E is formed by opening at least one side of the horizontal groove 5c to a vertical main groove 3. A crossing part J formed by crossing a virtual extending part 10 of the horizontal groove 5c and the vertical main groove 3 in the opening end E forms a three-forked road 11 facing to a groove wall 4W of the adjacent rib shaped land part 4 with the vertical main groove 3 sandwiched. The horizontal groove 5c having the three-forked road 11 includes a constricted part 14 with a minimum groove cross sectional area between both of the opening ends E, E, and the groove cross sectional area is gradually increased at least toward the opening end E of the three-forked road 11 from the constricted part 14. COPYRIGHT: (C)2006,JPO&NCIPI |
